I'd say that probably none of the CRPGs ever made is an ideal one. Strange as it may sound, because I love many. I suppose any game has got some quirks or things I (we) have to put up with. Some worse than others, some just strange, little, unnecessary choices. It makes me sad to see players often shunning the whole product (game) for a few of these. We've always had it like that. Most of the things in our lives are like that. So, I believe a game doesn't have to be ideal per-se to be a 10/10 experience. I think these are really two different points, sadly not many people seem to share that thought.
Anyway, as for the list of the greatest CRPG experiences for me:
1. Betrayal at Krondor for emphasizing the importance of good characters and story in the CRPG experience.
2. KotCs for awesome AD&D stuff out of the blue in a RPG-dry season.
3. Dark Sun I+II, which are both cute and gritty.
4. ToEE, River of Time, and Wizards and Warriors for being the truest diamonds in the rough.
5. Baldur's Gates for being the first truly epic gaming experience. It actually even intimidated me out of playing initially, heh.
6. Icewind Dale II for being one of the first PC CRPGs to allow for an infinite number of builds and thus replays.
7. Albion (1996) for being a pure CRPG love letter.
8. Wizardry VII. Very frustrating, fondest of memories. My friend was flamberghasted when I told him I could fathom the number and kind of enemies from the type of my hardrive's screeching prior to loading a battle.
9. Last but not least, Wasteland 3.
I'm sure I'll get a lot of flak from people here, but I'd say the last game is the one of closest things to an ideal CRPG. Not the best of experiences, but the ideal CRPG mynd you. It's because all the necessary features of the CRPG genre are present, none are really bad, some are good, and some even shine. The devs chose the golden middle-grounds for most of the game's features, and that means the game is accessible to both casual players and CRPG veterans.